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iGCSE stoichiometry quiz

Total questions: 15

Worksheet time: 49mins

Name
Class
Date
1.

The equation shows the reaction between magnesium and sulfuric acid.

[Ar: H, 1; O, 16; Mg, 24; S, 32]

Mg + H2SO4 → MgSO4 + H2

In this reaction, which mass of magnesium sulfate is formed when 6g of magnesium react with excess sulfuric acid?

a)

8

b)

24

c)

30

d)

60

2.

Two atoms of magnesium, Mg, react with one molecule of oxygen, O2. What is the formula of the product?

a)

MgO

b)

MgO2

c)

Mg2O

d)

Mg2O2

3.

What is the relative formula mass, Mr, of CaCO3?

Ar Ca: 40, C: 12, O:16

a)

50

b)

68

c)

100

d)

204

4.
a)

A

b)

B

c)

C

d)

D

5.

The complete combustion of methane produces CO2 and steam.

CH4 + 2O2 -> 2H2O (g) + CO2 (g)

Tick ALL boxes that are correct

a)

the empirical formula of methane is CH4

b)

The number of atoms in 1 mole of methane is 4 x 6 x 1023

c)

1 mole of methane produce 72 dm3 of gaseous products at rtp

d)

1 mole of methane occupies a volume of 12 dm3 at rtp

6.

Calcium carbide and water react to produce ethyne and calcium hydroxide. What is the volume of C2H2 in dm3 produced when 45g of water reacts completely? (Ar: H:1, O:16)

a)

72

b)

30

c)

24

d)

6

7.

What is volume of CO2 in dm3 produced when 21g of magnesium carbonate MgCO3 reacts completely with excess acid?

a)

4

b)

8

c)

6

d)

2

8.

Calcium carbonate undergoes thermal decomposition to form calcium oxide and carbon dioxide. What mass of CaO, in grams, is formed when 60g of CaCO3 decomposes?

a)

28

b)

18.5

c)

60

d)

33.6

9.

How many kg of aluminium oxides are formed from 5.4 kg of aluminium reacting with excess oxygen? (Ar: Al 27, O:16)

a)

5.4

b)

88

c)

10.2

d)

33.6

10.

Magnesium nitride and water react to produce a precipitate of magnesium hydroxide and ammonia gas.

How much magnesium nitride is needed to produce 87g of the precipitate?

Mg: 24

N: 14

O: 16

H: 1

a)

24 g

b)

50 g

c)

30 g

d)

12 g

11.

What is the concentration in mol.dm-3, or M (pronounced molar), of a solution of NaOH that contains 16 g of sodium hydroxide in 200 cm3 of distilled water?

Na: 23, O: 16, H: 1

Hint: ALWAYS convert volume of solution to dm3!

a)

2 mol.dm-3

b)

2.5 mol.cm-3

c)

0.2 mol.dm-3

d)

1 mol.cm-3

12.

A substance is analysed and found to contain 26.57% potassium (Ar: 39), 35.36% chromium (Ar: 52) and 38.07% oxygen (Ar: 16) by mass. What's the empirical formula?

a)

KCr2O7

b)

K2CrO7

c)

K2Cr2O5

d)

K2Cr2O7

13.

Substance mysterious X was analyzed to contain 40.00% carbon (Ar: 40), 6.67% hydrogen (Ar: 1) and 53.33% oxygen (Ar: 16) by mass. It has a relative molecular mass of 60.0 gmol-1.

What is its molecular formula?

a)

C4H8O4

b)

C6H12O6

c)

C2H4O2

d)

CH2O

14.

A student thermally decomposes 24.8 g of CuCO3 (white powder in picture) and obtains 11.2g of CuO (black powder) together with carbon dioxide gas.


CuCO3 -> CuO + CO2


Ar Cu: 64, C: 12, O: 12


What is the percentage yield of CuO made?

a)

55%

b)

70%

c)

82%

d)

90%

15.

A sample of chalk (limestone) with a mass of 1.90 g was reacted with excess HCl. The volume of gas given off was measured using a gas syringe. 0.36 dm3 of gas was collected at r.t.p


CaCO3 + 2HCl -> CaCl2 + CO2 + H2O


What is the percentage purity of the chalk?

Message me for hints if you're unsure!

a)

75%

b)

88%

c)

90%

d)

98%